The anatomic and pathophysiologic features of tricuspid valvar dysplasia are discussed in the light of two cases observed during fetal life which progressed with an unexpectedly favorable course. Some fetal echocardiographic features are proposed to explain this outcome. First, absence of associated cardiovascular abnormalities; second, clear separation between well represented right ventricular walls and the tricuspid valvar leaflets; third, normal proximal insertion of the tricuspid leaflets and, fourth, normal dimensions of the pulmonary trunk. We recommend karyotyping because of the possible association of this malformation with an aneuploid karyotype. We also describe transitory functional atresia of the pulmonary valve at birth, as far as we know for the first time, in a neonate that had normal forward flow of blood as seen on Doppler sampling in fetal life.
